1. Field of the Invention
This invention describes a novel method of inspecting unidentified packages placed on the floor or ground, or on desktops or counters. The method uses a transmissive x-ray system mounted on a small mobile platform such as robots.
2. Description of the Related Art
Majority of x-ray systems in use today are fixed or stationary systems like the ones seen at airports for scanning bags. If an unidentified bag or object is found on the lobby of an airport, to examine it, the object or the bag has to be picked up and placed on the belt of a the stationary x-ray system. This not only puts the risk of the bomb squad members handling the object at risk, but any movement of the bag can trigger an explosion causing serious fatalities and damages.
An alternative approach used is to use small hand held x-ray sources which are hand carried by a member of the bomb squad and placed in close proximity of the unidentified bag. On the other side of the bag is then placed a film or detector panel which is sensitive to x-rays and can record an image of the object when x-rays pass through it. The problem with this approach is that the hand held x-ray sources are pulsed, hence their flux is low which results in a low signal to noise ratio and hence a low quality image unless long exposure times are used. A greater problem with such sources is that the high voltage required to generate the x-rays is generated by using some sort of a spark technology that produces a flash of an x-ray, producing x-rays in such a fashion does not facilitate itself to controlling reasonably well enough the amplitude of the high voltage and hence the energy of the x-ray. If one is able to better control the x-ray energy, one can scan the object with different energies and select an image that is best created by an optimal energy level for that particular object. For example, when scanning soft or low density objects, one would like to set the energy level low, using higher energy, would give a washed out effect on the scanned image. Further using different energy levels, one can make a determination of atomic number and density and make more accurate prediction if the contents of the bag or object are explosive in nature or not.
In addition to not being able to set the energy accurately enough, there is a huge risk to human personnel who hand carry the x-ray source and the film or detector panel and place them close to the suspected object or bag.
If an object or bag is left on a desk top, there might not be enough room on the desk top to place the hand held x-ray source on one side and the detector on the other side of the bag.
Other scanning systems include mobile systems that are large and mounted on a truck, these are not suitable for imaging small objects. Such systems can not produce images of those portions of the object that are close to the ground because the x-ray source is located at a much higher level. This is important as explosives might be located on the lower portions of the bag or object.
Accordingly, the objects of this invention are to overcome the above limitations as stated next.